A bonding material comprising metal particles coated with an organic substance having carbon atoms of 2 to 8, wherein the metal particles comprises first portion of 100 nm or less, and a second portion larger than 100 nm but not larger than 100 μm, each of the portions having at least peak of a particle distribution, based on a volumetric base. The disclosure is further concerned with a bonding method using the bonding material.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A bonding method for electrically connecting an electrode of an electronic element and a wiring of a wiring substrate, comprising: applying a bonding material comprising a first portion of metal particles having an average particle size of 100 nm or less, the metal particles being coated with an organic substance having carbon atoms of 2 to 8, wherein the first portion of metal particles has at least one first peak of a particle size distribution based on a volumetric base to a bonding face where the electrode of the electronic element is to be placed on the wiring substrate, and a second portion of metal particles having an average particle size of 100 nm to 100 μm, wherein the second portion of metal particles comprises aggregated particles produced by evaporating a solvent from the metal particles of 100 nm or less coated with an organic substance having carbon atoms of 2 to 8, and wherein the second portion of metal particles has at least one second peak of a particle size distribution, different from the at least one first peak, based on a volumetric base to a bonding face where the electrode of the electronic element is to be placed on the wiring substrate; mounting an electronic element on the bonding material; and heating the electrode at least in the bonding area under a pressure thereby bonding the electrode and the wiring of the wiring substrate.
2. The bonding method according to claim 1 , wherein the heating temperature is 40 to 400° C.
3. The bonding method according to claim 1 , wherein the metal particles are at least one member selected from the group consisting of gold, silver and copper.
4. The bonding method according to claim 1 , wherein the organic substance contains oxygen atoms, nitrogen atoms and/or sulfur atoms.
5. The bonding method according to claim 1 , wherein the organic substance is at least one organic compounds having a radical selected from the group consisting of an alcohol group, amino group, carboxyl group, carbonyl group, aldehyde group and sulfanyl group.
6. The bonding method according to claim 1 , wherein a weight ratio of the first portion in the total metal particles is larger than 0.001, but smaller than 100.
7. The bonding method according to claim 1 , wherein the metal particles are dispersed in an organic solvent.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
May 3, 2011
September 2, 2014
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